how to use schema in our website, i have site uaenationalday.info/ i want to use schema. Can you please help me out.

Hello you need to override the item.php file, getk2.org/documentation/tutorials/174-templating-with-k2-and-the-concepts-of-sub-templates , and apply schema.org's tags.

You can find an example here: github.com/kricore/Advanced-templating-with-K2/blob/master/default/item.php
Do not use any of it's code as is, apart from HTML stuff.